Hard Reset SAMSUNG S5830i Galaxy Ace

First method:

1. At the beginning turn off the phone by using the Power button.
2. In the next step press and hold together: Home button + Power button.
3. Release held keys when the Recovery mode appears on the screen.
4. Then select  "wipe data / factory reset" using Volume buttons to navigate and Home buttonto confirm.
   
5. Choose "Yes -- delete all user data" to confirm the whole operation.
6. After that select option "reboot system now".
7. Well done! The hard reset has just been performed.

Second method:

1. Start by turninng on the device.
2. From the Home Screen go to Menu and then to Settings.
3. Tap Privacy and then Factory data reset.
4. Afterwards choose Reset device.
5. To confirm your choice select Erase everything.
6. That's all.

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.